Mississippi Interior Salt Basin Research Articles

Reprint of “Organic petrology of the Aptian-age section in the downdip Mississippi Interior Salt Basin, Mississippi, USA: Observations and preliminary implications for thermal maturation history”

This study identifies a thermal maturity anomaly within the downdip Mississippi Interior Salt Basin (MISB) of southern Mississippi, USA, through examination of bitumen reflectance data from Aptian-age strata (Sligo Formation, Pine Island Shale, James Limestone, and Rodessa Formation). U.S. Geological Survey (USGS) reconnaissance investigations conducted in 2011–2012 examined Aptian-age thermal maturity trends across the onshore northern Gulf of Mexico region and indicated that the section in the downdip MISB is approaching the wet gas/condensate window (Ro ~1.2%). A focused study in 2012–2013 used 6 whole core, one sidewall core, and 49 high-graded cutting samples (depth range of 13,000–16,500ft [3962.4–5029.2m] below surface) collected from 15 downdip MISB wells for mineralogy, fluid inclusion, organic geochemistry, and organic petrographic analysis. Based on native solid bitumen reflectance (Ro generally >0.8%; interpreted to be post-oil indigenous bitumens matured in situ), Ro values increase regionally across the MISB from the southeast to the northwest. Thermal maturity in the eastern half of the basin (Ro range 1.0 to 1.25%) appears to be related to present-day burial depth and shows a gradual increase with respect to depth. To the west, thermal maturity continues to increase even as the Aptian section shallows structurally on the Adams County High (Ro range 1.4 to >1.8%). After evaluating the possible thermal agents responsible for increasing maturity at shallower depths (i.e., igneous activity, proximity to salt, variations in regional heat flux, and uplift), we tentatively propose that either greater paleoheat flow or deeper burial coupled with uplift in the western part of the MISB could be responsible for the thermal maturity anomaly. Further research and additional data are needed to determine the cause(s) of the thermal anomaly.

Organic petrology of the Aptian-age section in the downdip Mississippi Interior Salt Basin, Mississippi, USA: Observations and preliminary implications for thermal maturation history

This study identifies a thermal maturity anomaly within the downdip Mississippi Interior Salt Basin (MISB) of southern Mississippi, USA, through examination of bitumen reflectance data from Aptian-age strata (Sligo Formation, Pine Island Shale, James Limestone, and Rodessa Formation). U.S. Geological Survey (USGS) reconnaissance investigations conducted in 2011–2012 examined Aptian-age thermal maturity trends across the onshore northern Gulf of Mexico region and indicated that the section in the downdip MISB is approaching the wet gas/condensate window (Ro ~1.2%). A focused study in 2012–2013 used 6 whole core, one sidewall core, and 49 high-graded cutting samples (depth range of 13,000–16,500ft [3962.4–5029.2m] below surface) collected from 15 downdip MISB wells for mineralogy, fluid inclusion, organic geochemistry, and organic petrographic analysis. Based on native solid bitumen reflectance (Ro generally >0.8%; interpreted to be post-oil indigenous bitumens matured in situ), Ro values increase regionally across the MISB from the southeast to the northwest. Thermal maturity in the eastern half of the basin (Ro range 1.0 to 1.25%) appears to be related to present-day burial depth and shows a gradual increase with respect to depth. To the west, thermal maturity continues to increase even as the Aptian section shallows structurally on the Adams County High (Ro range 1.4 to >1.8%). After evaluating the possible thermal agents responsible for increasing maturity at shallower depths (i.e., igneous activity, proximity to salt, variations in regional heat flux, and uplift), we tentatively propose that either greater paleoheat flow or deeper burial coupled with uplift in the western part of the MISB could be responsible for the thermal maturity anomaly. Further research and additional data are needed to determine the cause(s) of the thermal anomaly.

Origins of gypsum in deep carbonate reservoirs: Implications for hydrocarbon exploration and production

Gypsum can form penecontemporaneously in carbonate sediments, and it may be altered to anhydrite during burial. Some workers have suggested that gypsum dehydration is complete at burial depths of 3500 ft (1067 m); however, gypsum has been documented at depths as great as 13,100 ft (3993 m). Two examples of deeply buried gypsum illustrate contrasting origins. Gypsum in the Permian San Andres Formation in the Permian Basin of west Texas at a depth of 6000 ft (1829 m) occurs as anhydrite nodules with an outer rind of gypsum, suggesting that anhydrite was rehydrated to gypsum by interaction with interstitial brines. In contrast, gypsum in the carbonate beds of the Cretaceous Ferry Lake Anhydrite of the Mississippi Interior Salt Basin at 13,100 ft (3993 m) occurs as gypsum nodules with a rind of anhydrite, suggesting that the gypsum is primary and in the process of dehydration to anhydrite. These contrasting origins are likely a function of evaporite and carbonate stratigraphy. In the Permian Basin, a thick section of carbonate rocks is overlain by a relatively thin section of evaporites. In the Mississippi Interior Salt Basin, carbonates are interbedded with multiple evaporite beds, which inhibit circulation of interstitial brines. The burial temperature, pressure, and salinity of these formations suggest that gypsum could be preserved as primary or secondary gypsum. The presence of gypsum in reservoir rocks can affect porosity calculations, especially calculations using neutron porosity logs, which measure bound water of hydration in gypsum as porosity. Identification of gypsum at the depth of 13,100 ft (3993 m) indicates that log estimates of porosity in some deep carbonate reservoirs containing gypsum could have significant porosity and water saturation measurement errors.

Citronelle Dome: A giant opportunity for multizone carbon storage and enhanced oil recovery in the Mississippi Interior Salt Basin of Alabama

The Citronelle Dome is a giant, salt-cored anticline in the eastern Mississippi Interior Salt Basin of southern Alabama that is located near several large-scale, stationary, carbon-emitting sources in the greater Mobile area. The dome forms an elliptical, four-way structural closure containing opportunities for CO2-enhanced oil recovery (CO2-EOR) and large-capacity saline reservoir CO2 sequestration. The Citronelle oil field, located on the crest of the dome, has produced more than 169 million bbl of 42–46 API gravity oil from sandstone bodies in the Lower Cretaceous Rodessa Formation. The top seal for the oil accumulation is a thick succession of shale and anhydrite, and the reservoir is underfilled such that oil-water contacts are typically elevated 30–60 m (100–200 ft) above the structural spill point. Approximately 31–34% of the original oil in place has been recovered by primary and secondary methods, and CO2-EOR has the potential to increase reserves by up to 20%. Structural contour maps of the dome demonstrate that the area of structural closure increases upward in section. Sandstone units providing prospective carbon sinks include the Massive and Pilot sands of the lower Tuscaloosa Group, as well as several sandstone units in the upper Tuscaloosa Group and the Eutaw Formation. Many of these sandstone units are characterized by high porosity and permeability with low heterogeneity. The Tuscaloosa-Eutaw interval is capped by up to 610 m (2000 ft) of chalk and marine shale that are proven reservoir seals in nearby oil fields. Therefore, the Citronelle Dome can be considered a major geologic sink where CO2 can be safely stored while realizing the economic benefits associated with CO2-EOR.

Upper Jurassic thrombolite reservoir play, northeastern Gulf of Mexico

In the northeastern Gulf of Mexico, Upper Jurassic Smackover inner ramp, shallow-water thrombolite buildups developed on paleotopographic features in the eastern part of the Mississippi Interior Salt basin and in the Manila and Conecuh subbasins. These thrombolites attained a thickness of 58 m (190 ft) and were present in an area of as much as 6.2 km2 (2.4 mi2). Although these buildups have been exploration targets for some 30 yr, new field discoveries continue to be made in this region. Thrombolites were best developed on a hard substrate during a rise in sea level under initial zero to low background sedimentation rates in low-energy and eurytopic paleoenvironments. Extensive microbial growth occurred in response to available accommodation space. The demise of the thrombolites corresponded to changes in the paleoenvironmental conditions associated with an overall regression of the sea. The keys to drilling successful wildcat wells in the thrombolite reservoir play are to (1) use three-dimensional seismic reflection technology to find paleohighs and to determine whether potential thrombolite reservoir facies occur on the crest and/or flanks of these features and are above the oil-water contact; (2) use the characteristics of thrombolite bioherms and reefs as observed in outcrop to develop a three-dimensional geologic model to reconstruct the growth of thrombolite buildups on paleohighs for improved targeting of the preferred dendroidal and chaotic thrombolite reservoir facies; and (3) use the evaporative pumping mechanism instead of the seepage reflux or mixing zone models as a means for assessing potential dolomitization of the thrombolite boundstone.

Structure and evolution of the central Gulf of Mexico continental margin and coastal plain, southeast United States

As in many continental margins, Mesozoic rifting in the Gulf of Mexico trended subparallel to older tectonic structures created by opening and closure of a prior ocean basin. Unlike the situation in most other margins, however, extension in the Gulf of Mexico did not involve widespread reactivation of these older tectonic features. This difference may be related to the unusual facts that (1) the antecedent passive continental margin was a transform rather than a rift margin and (2) the prior orogeny did not substantially thicken the crust. In order to characterize the interaction between Mesozoic rifting and prior tectonic events, two geophysical transects were constructed across the central Gulf of Mexico coastal plain and continental shelf. The transects show that the early Paleozoic passive continental margin buried beneath the late Paleozoic Ouachita orogen was little affected by compressional tectonism or Mesozoic extension during opening of the Gulf of Mexico. The thickness of the crust on this ancient margin decreases from 35 km to 10 km over a distance of only 50 km, consistent with previous interpretations that this was a transform margin. The Ouachita fold-and-thrust belt is shown to be a thin-skinned doubly vergent orogen that formed above a well-preserved southward-dipping subduction system. Relict Cambrian oceanic crust may exist beneath the southern part of the orogen, but its presence is not required by the data. The thin crust and shallow mantle in the Ouachita suture created a zone of relatively high strength that acted as a barrier to Mesozoic extension, which is restricted to regions south of the orogen. Extension was initially distributed over a broad area that included the Mississippi Interior Salt Basin and regions south of the Wiggins Arch. Extension became progressively more focused south of the Wiggins Arch with time, culminating in the onset of seafloor spreading beneath the modern continental rise. Mesozoic extension factors are β = 1.4–1.9 beneath the Mississippi Interior Salt Basin, β ≈ 2.9 immediately south of the Wiggins Arch, and β ≈ 4 adjacent to the oldest oceanic crust in the central Gulf of Mexico.

Upper Jurassic (Oxfordian) Smackover carbonate petroleum system characterization and modeling, Mississippi Interior Salt Basin area, northeastern Gulf of Mexico, USA

The Upper Jurassic (Oxfordian) Smackover Formation is a prolific oil and gas reservoir in the northern Gulf of Mexico, including the Mississippi Interior Salt Basin area. The Smackover petroleum system is categorized as a giant petroleum system and ranks fourth among recognized Upper Jurassic petroleum systems. In the Mississippi Interior Salt Basin area, the components of the Smackover petroleum system include pre rift, syn rift and post rift siliciclastic, evaporite, and carbonate underburden and overburden rocks, Smackover subtidal lime mudstone source rocks, uppermost Smackover anhydrite and Buckner Anhydrite Member subaqueous saltern and sabkha seal rocks, and upper Smackover shoal complex and tidal flat complex packstone, grainstone, boundstone and dolostone reservoir rocks. The critical events include the initiation of the generation of crude oil, the commencement of hydrocarbon expulsion, the initiation of hydrocarbon migration, and the entrapment of hydrocarbons during the Early to Late Cretaceous. The critical moment for the Smackover petroleum system is the time of peak hydrocarbon expulsion in the mid to late Early Cretaceous in basin center areas and mid to latest late Cretaceous in areas along the northern basin margin. *** DIRECT SUPPORT *** A00QA034 00003

Transgressive-regressive cycles in Lower Cretaceous strata, Mississippi Interior Salt Basin area of the northeastern Gulf of Mexico, USA

Four transgressive-regressive (T-R) cycles and five T-R subcycles have been recognized in Lower Cretaceous strata of the northeastern Gulf of Mexico. These T-R cycles are the LKEGR-TR 1 (Lower Cretaceous, Eastern Gulf Region) (upper Valanginian–upper Aptian), the LKEGR-TR 2 (upper Aptian–middle Albian), the LKEGR-TR 3 (middle–upper Albian), and the LKEGR-TR 4 (upper Albian–lower Cenomanian) cycles. The LKEGR-TR 1 Cycle consists of three subcycles: LKEGR-TR 1–1 (upper Valanginian–lower Aptian), LKEGR-TR 1–2 (lower Aptian) and LKEGR-TR 1–3 (upper Aptian) subcycles. The LKEGR-TR 2–1 (upper Aptian–lower Albian) and the LKEGR-TR 2–2 (lower–middle Albian) subcycles constitute the LKEGR-TR 2 Cycle. The LKEGR-TR 3 and the LKEGR-TR 4 cycles consist of a single T-R cycle.Recognition of these T-R cycles is based upon stratal geometries, nature of cycle boundaries, facies stacking patterns within cycles, and large-scale shifts in major facies belts. The T-R subcycles are characterized by shifts in major facies belts that are not of the magnitude of a T-R cycle. The cycle boundary may be marked by a subaerial unconformity, ravinement surface, transgressive surface or surface of maximum regression. A single T-R cycle consists of an upward-deepening event (transgressive aggrading and backstepping phases) and an upward-shallowing event (regressive infilling phase). These events are separated by a surface of maximum transgression. The aggrading phase marks the change from base-level fall and erosion to base-level rise and sediment accumulation; this phase signals the initiation of the creation of shelf-accommodation space. The marine transgressive and flooding events of the backstepping phase are widespread and provide regional correlation datums. Therefore, these T-R cycles and subcycles can be identified, mapped, and correlated in the northeastern Gulf of Mexico area. The progradational events associated with the regressive infilling phase represent a major influx of siliciclastic sediments into the basin, the development of major reef build-ups at the shelf margin, and a significant loss of shelf-accommodation space. These T-R cycles are interpreted to be the result of the amount of and change in shelf-accommodation due to a combination of post-rift tectonics, loading subsidence, variations in siliciclastic sediment supply and dispersal systems, carbonate productivity and eustasy associated with a passive continental margin. The T-R cycles, where integrated with biostratigraphic data, can be correlated throughout the northern Gulf of Mexico region and have the potential for global correlation of Lower Cretaceous strata.

ABSTRACT: Sequence Stratigraphy and Petroleum Potential of Lower Cretaceous Strata, Mississippi Interior Salt Basin

Abstract Four depositional sequences of 4 to 15 million years' duration have been recognized in Lower Cretaceous strata of the Mississippi Interior Salt Basin. These are the LKEGR-1 (Lower Cretaceous, Eastern Gulf Region) (132 to 117 Ma), LKEGR-2 (117 to 109 Ma), LKEGR-3 (109 to 103 Ma), and LKEGR-4 (103 to 99 Ma) depositional sequences. The LKEGR-1 depositional sequence includes the Hosston and Sligo formations (Hauterivian to Aptian age). The LKEGR-2 depositional sequence includes the Pine Island, James, Rodessa, and Ferry Lake formations (Aptian to Albian age). The LKEGR-3 depositional sequence includes the Mooringsport and Paluxy formations (Albian age). The LKEGR-4 depositional sequence includes the Andrew and Dantzler formations (Late Albian age). These depositional sequences can be identified and mapped throughout the basin. They are interpreted to be the result of a combination of post-rift tectonics, variations in siliciclastic sediment supply and dispersal systems, and eustasy. To date, 3.3 Tcf of natural gas and 791 million barrels of oil have been produced from Lower Cretaceous petroleum reservoirs in the Mississippi Interior Salt Basin. Most of the oil production is from the LKEGR-2 depositional sequence, and the majority of the natural gas is from the LKEGR-1 depositional sequence. Based on sequence stratigraphic analysis, these reservoirs have considerable petroleum potential for continued exploration and production.

Abstract: Integrated Lithostratigraphic and Biostratigraphic Approach to Sequence Stratigraphic Analysis: Lower Cretaceous Section, Mississippi Interior Salt Basin

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ABSTRACT: Petroleum Plays in the Mississippi Interior Salt Basin

ABSTRACT: Petroleum Plays in the Mississippi Interior Salt Basin

Abstract: Source rocks, maturation, and seals in carbonate systems of the Mississippi Interior salt basin

Abstract: Source rocks, maturation, and seals in carbonate systems of the Mississippi Interior salt basin

Abstract: Stratigraphic Framework of the Mesozoic Sediments of the Mississippi Interior Salt Basin 

ABSTRACT The stratigraphic framework of the Mississippi Interior Salt Basin (MISB) was studied to determine the burial and thermal history of the basin. Wireline logs, predominantly SP and resistivity but supplemented by gamma ray, sonic, and neutron/density logs, and lithologic and sample logs from 48 wells comprise the information base. Five cross sections were generated, including a strike section and four dip sections. The geographic extent of the dip sections allows tracking formational changes in the basin, particularly the change from predominantly siliciclastic to carbonate sediments which most of the formations display, and the diachroneity of the formational contacts. Figure 1. Time-stratigraphic cross section of Mississippi Interior Salt Basin along generalized line from Yazoo County to the Wiggins Arch in George County, Mississippi. The change from siliciclastic to carbonate sediments presents special problems when correlating from onshore to offshore regions of the Gulf of Mexico. Typically, formational boundaries in onshore areas can be recognized on the basis of characteristic wireline log signatures that reflect lithologic disparities. South of the Wiggins Arch, where much of the Mesozoic section is carbonate, biostratigraphy is increasingly used to define formational boundaries. Although the presence of microfossils is reported in sample and lithologic logs from many wells and formations in the MISB, very little of this paleontological information has been published and remains an area of future study. Tectonic subsidence of the MISB occurred largely during the Jurassic and Early Cretaceous, as variances of the thicknesses of these two systems are much greater than that of the Upper Cretaceous System. The literature indicates that other salt basins occurring on thick transitional crust have analogous depositional systems, suggesting that stratigraphic models developed in one basin can be applied to other, less studied salt basins. End_of_Record - Last_Page 25-------

Abstract: Modeling of the Burial and Thermal Histories of Strata in the Mississippi Interior Salt Basin 

ABSTRACT Burial history and thermal maturation analyses have been performed for strata of the Mississippi Interior Salt Basin. The tectonic and depositional histories form the foundation for the modeling. Five regional cross sections consisting of 48 wells, structural maps, and isopach maps comprise the basis for this study. Information interpreted from well samples, cross sections, and subsurface maps include biostratigraphic, paleoenviron-mental, lithologies and stratigraphic thickness of the units, com-paction, sediment accumulation and subsidence rates, uncon-formities and faulting. Basin modeling indicates that variation in sediment accumulation rate is related to lithology, unit thickness, and dura-tion of deposition. The highest mean sediment accumulation and tectonic subsidence rates were recorded for Late Jurassic and Early Cretaceous strata. Thermal maturity modeling was accomplished utilizing vitrinite reflectance, thermal alteration index, Tmax, bottom hole temperature, type of kerogen and total organic carbon data. Maturity modeling indicates that Upper Jurassic carbonate mud-stones (rich in algal kerogen) were effective regional source rocks throughout the basin. Oil generation commenced from these carbonate mudstones in the Early to Late Cretaceous and continued into the Paleogene. Upper Cretaceous black shales (rich in herbaceous kerogen) were effective local source rocks in the area of the Perry sub-basin. Oil generation was initiated from these shales in the Paleogene. Lower Cretaceous shales are possible local source rocks in the Perry sub-basin area. The burial and thermal histories of Paleogene shales were not conducive for the generation of hydrocarbons in this basin.

Abstract: Key to Exploration in the Mississippi Interior Salt Basin and Related Sub-Basins, Eastern Gulf Coastal Plain 

Abstract: Key to Exploration in the Mississippi Interior Salt Basin and Related Sub-Basins, Eastern Gulf Coastal Plain 

Abstract: Joint Systems Along the Northeast Margin of the Mississippi Interior Salt Basin, Alabama 

ABSTRACT Joints are commonly overlooked structures in Mesozoic-Cenozoic strata of the eastern Gulf Coast basin, yet significant hydrocarbon accumulations are in fractured and conventional reservoirs in this area. Two orthogonal joint systems are developed in Cenozoic strata along the northeastern margin of the Mississippi interior salt basin. System 1 joints strike subparallel to salt-related faults and fold axes. System 2 joints strike parallel to many modern hillslopes and appear to postdate regional faulting. System 2 joints apparently are forming in response to neotectonic stresses associated with regional unroofing and valley incision and probably do not extend downward to reservoir depths (~1,000 to 4,000 m). Orientation data suggest that system 1 joints formed in the same regional stress field as the salt-related faults. Therefore, system 1 joints and cross joints are predicted to exist at reservoir depths where they may form permeability pathways affecting hydrocarbon recovery.

Dry Creek Salt Dome, Mississippi Interior Salt Basin

Recent drilling of salt dome flanks in the Mississippi Salt basin has resulted in important new discoveries and the opening of a frontier play. This play is focused on gas/condensate reserves in several Cretaceous formations, most notably the Upper Cretaceous Eutaw and lower Tuscaloosa intervals and Lower Cretaceous Paluxy and Hosston formations. As many as eight domes have been drilled thus far; sandstones in the upper Hosston Formation comprise the primary target. Production has been as high as 3-5 Mcf* and 500-1200 bbl of condensate per day, with estimated ultimate reserves in the range of 0.2 to 1.5 MBOE (million barrels oil equivalent) per well. As typified by discovery at Dry Creek salt dome, traps are related to faulting, unconformities, and updip loss of permeability. Previous drilling at Dry Creek, and in the basin generally, avoided the flank areas of most domes, due to geologic models that predicted late-stage (Tertiary) piercement and breached accumulations. Recent data from Dry Creek and other productive domes suggest that growth was episodic and that piercement of Tertiary strata did not affect deeper reservoirs charged with hydrocarbons in the Late Cretaceous.

Abstract :Revitalization of an Old Play--Shallow, Piercement Salt Domes in the Mississippi Interior Salt Basin

Abstract :Revitalization of an Old Play--Shallow, Piercement Salt Domes in the Mississippi Interior Salt Basin

Eustatic Effects on Sandstone and Carbonate Diagenesis in Jurassic Reservoirs of the Mississippi Interior Salt Basin: ABSTRACT

Eustatic Effects on Sandstone and Carbonate Diagenesis in Jurassic Reservoirs of the Mississippi Interior Salt Basin: ABSTRACT

Restoration of Cross Sections Above Intrusive Salt Domes

The applicability of bed-length restoration to the sequence above a vertical intrusion of salt was tested on an experimental model that included deposition of units during uplift. Restoration of the model resulted in an apparently unbalanced cross section due to excess bed length in the pre-growth interval. The excess bed length was due to significant internal strain. For a correct restoration, it is thus important to distinguish between the growth and pre-growth sequences. The thinning index, which quantifies the thinning onto the uplift, aids in making this distinction. A thinning index vs. depth curve has a sharp inflection at the top of the pre-growth sequence. The pre-growth sequence is restored by area balancing. The growth sequence deforms mainly by formation of a restal graben, with little other strain. Sequential restoration of growth intervals shows the growth history of the dome. When applied to the Pool Creek salt dome from the Mississippi Interior Salt basin, the methods developed for the model served to separate the pre-growth from the growth sequence and to indicate a growth history of vertical intrusion changing through time to vertical intrusion plus regional extension.